| abstract |
The present invention relates to a method for recovering rare earth metals from waste sulphate materials, such as waste gypsum, which is a known secondary resource of rare earth metals and widely present e.g. in areas, where industrial phosphate production takes place. The present invention combines sulphate reduction treatment, such as bioreduction with sulphate reducing bacteria, and magnetic separation, which is based on an exceptionally high magnetic susceptibility of rare earth compounds compared to e.g. calcium compounds in such reductively pretreated gypsum precipitate. |